I can't address the scientific part of your question, but I'm sure some of our fellow readers will...

...but you can probably reduce your water intake during the times you're touring and such without harming your weight loss. You might consider making up as much as you can in the later partof the day or possibly some extra after dinner. It may cause some extra trips to the bathroom during the night, but if you're truly worried about it, it may be worth trying.

Have a great vacation!

Donald